【摘要】 对超高强钢和铝合金的研究表明,在压—压交变载荷下缺口前端能引发疲劳裂纹,但其门槛值比拉应力高三倍。压应力下缺口裂纹长到一定尺寸(如0.2～0.5mm)后就将停止扩展。如果压应力的最小载荷(绝对值)接近零,则裂纹容易形成(门栏值和拉应力相近),且能扩展较长的距离。更多还原

【Abstract】 For ultra-high strength steel and aluminum alloy , a fatigue crack could initiate from a notch tip under a cyclic compressive load. The th-resholp value Δzσth or ΔKth(ρ) for fatigue crack initiation under a compressive load was four times as high as that under tensile load . The crack grew at a decreasing rate until eventually it stopped growing under cyclic compressive load and the maximal length of the fatigue crack was only 0.2-0.5mm. The crack nucleation under comdressive stress became easier and the propagation distance of the fatigue crack was longer if the mimimum cyclic compressive load was near zero.更多还原